Acrylic fibers



United States Patent Ofice 3,434,874 Patented Mar. 25, 1969 U.S. Cl. Ill7138.8 2 Claims ABSTRAflT OF THE DISLOSURE Textile fibers of acrylic polymer having on the surfaces thereof a finish composition consisting essentially, by weight, of 1.25 to 1.75 parts of a salt of a partial ester of phosphoric acid per part of a paratfin wax. The fibers produce antistatic yarns having good knittability.

This invention relates to a finishing of synthetic fibers, and in particular concerns finishing compositions which will result in spun yarns having good knittability. It is also concerned with finishes which will prevent the accumulation of static charges on the finished fibers.

Knitting yarns spun from staple fibers have low twist in order to obtain high bulk, and, as a result of the low twist the yarns have low strength, usually expressed as Lea Product. Knitting imposes a stress on the yarn and some yarns require special finishes to make them strong enough to knit and to reduce stress in knitting. Such yarns can be treated with a wax at the knitting machine but this is inconvenient, can result in accidental choice of an improper wax and it is ditficult to apply finish uniformly at this state. Such finishes often cause difficulties in dyeing because of non-uniformity.

It is desirable for the fiber manufacturer to supply knitter or other user a fiber having on it a suitable knitting finish to minimize problems such as just described. However, such a finish must not interfere with the conversion of the fiber into yarn by carding and spinning of staple, by the Pacific Converter route, or by stretch-breaking and drafting of a tow. Waxes on fibers prior to spinning are usually regarded as undesirable because of adverse etfects on the processing of the fibers into yarns. The finish sometimes fouls the cards and causes neps in the roving and yarn.

The present invention provides a fiber treated with a wax-containing finish, which fiber will process satisfactorily through carding and spinning or through cutting on the Pacific Converter to give yarns which will knit satisfactorily without application of wax by the knitter. It also provides a fiber which will not accumulate a static charge during processing.

In accordance with the present discovery there is provided a newly discovered finish composition consisting essentially of paraffin wax and certain monoand diesters of phosphoric acid. Finish of this composition is applied by the filament manufacturer and results in a finish-containing filament that can be processed without difficulty in the usual manner, for example cut to staple and then spun to yarn, and after such processing can be used by knitting manufacturers without the need to apply at the knitting machines the special waxes heretofore necessary.

The phosphate esters in compositions according to the present invention are known and available commercially. These esters are made from fatty alcohols or alkyl phenols which have been condensed with an alkylene oxide, preferably ethylene oxide or propylene oxide. The phosphoric esters are used in the form of their alkali, alkaline earth, ammonium, amine or quaternary ammonium salts. Among the alcohols and alkyl phenols most suitable for making phosphoric acid esters for use in the present invention are the following: Lauryl or decyl alcohol condensed with 2 to 0 mols alkylene oxide; tetradecyl alcohol, hexadecyl alcohol or hexadecenyl alcohol condensed with 4 to 16 mols alkylene oxide; nonyl or decyl phenol condensed with 4 to 16 mols alkylene oxide; and octyl phenol condensed with 3 to 14 mols alkylene oxide.

The phosphoric esters can be either monoor diesters or, more conveniently, a mixture of the monoand diesters. The alcohols can likewise consist of mixtures and need not be a single specie.

A preferred composition is prepared by heating together a paratfin wax melting at 50 to 55 C. with a mixture of the monoand diesters of phosphoric acid made by reacting phosphoric acid with a product made by condensing lauryl alcohol with 4 mols ethylene oxide. The phosphoric acid ester is preferably used in the form of its sodium salt.

The finish composition of this invention is particularly suited to low strength yarns, that is, yarns of low Lea Product. The finish lubricates yarn to which it is applied and increases the strength, but more importantly it lowers the yarn-to-metal friction which decreases the running tension when the yarn is knit resulting in better knitting qualities. The yarn-to-yarn boundary friction is slightly decreased with a typical value of 0.21 where a control yarn having a conventional finish has a coefficient of 0.23. The hydrodynamic yarn-to-metal friction for a typical yarn is 0.26 versus 0.32 for a control yarn. The lower stress in the yarn during knitting, which results from the finish on the fiber, means fewer breaks and less defects in the knit fabric. Another property of finishes of this invention is a high degree of thixotrophy as shown by a high viscosity at low shear and low viscosity at high shear.

The finishes of this invention are especially useful for acrylic fibers of any of the usual deniers for textile applications but can also be used on other synthetic fibers, not only to improve knitting, but to lower static. Usually a concentration of 0.1 to 0.8% finish, and preferably 0.1 to 0.5%, based on fiber weight, is satisfactory. Higher concentrations within this range will reduce static to satisfactory levels at relative humidities as low as 20%. At higher relative humidities, lower concentrations of finish can be used. The finish can be applied by spraying, roller coating or any other known method as suits the convenience of the operator. Fibers finished according to this invention can be converted to yarns by the staple route or by treating tow on the Pacific Converter in which the tow is cut in a diagonal manner and converted to sliver.

The knittability of yarns is determined as follows: Two yarns are used as standards, one of which is known to knit satisfactorily commercially (No. 1) and one which knits with ditficulty (No. 2) because of breaks which result in holes in the knitted fabric. Knitting is done on a. 2l-gauge full-fashioned machine. The number of courses per inch on the machine is adjusted until breaks and holes occur with both yarns. Under these conditions, the satisfactory yarn (No. l) develops 2 to 10 holes in 15 minutes of knitting whereas the poor yarns (No. 2) develops 40 to holes in 15 minutes. vAny other yarn developing no more than 10 holes in 15 minutes of knitting is considered satisfactory.

The following examples are given to illustrate the invention but should not be construed to limit it. Parts and percentages given are by weight.

EXAMPLE I A bicomponent fiber is spun from two polymer compositions as follows:

Parts Composition I: Polyacrylonitrile 100 3 Composition H: Parts Terpolymer of:

Acrylonitrile, 93.6% Methyl acrylate, 6.0% 25 Sodium styrenesulfonate, .4% Copolymer of:

Acrylonitrile, 96% 1 Sodium styrenesulfonate, 4% "I Parts Refined paraifin wax melting at 53 C. and

having a density of 0.890 g./cc. 40 Sodium salt of a mixture of the monoand diesters of phosphoric acid and lauryl alcohol condensed with 4 mols ethylene oxide 60 The wax and phosphate are mixed and heated to 80 C. with stirring until a clear or nearly clear solution is obtained. This mixture is poured into 400 parts of water at 80 C. and agitated vigorously for minutes. The resulting dispersion is found to have a viscosity of 30.5 centistokes'. This dispersion contains solids.

This finish dispersion is applied to the tow by spraying so as to leave 0.3% of finish on the fiber after drying. The tow is then converted to sliver on a Pacific Converter (described in U.S. Patent 2,438,469 to Wilkie). The sliver is pin drafted and spun into 2/30 Worsted count (530 denier) yarn with 11 Z turns per inch (4.3 per cm.) in the singles and 5.7 S turns per inch (2.2 per cm.) in the ply. This yarn is found to have a Lea Product of 1273.

When the knittability test described above is applied to this yarn, it is found that after 15 minutes of knitting there are only 7 holes in the knit fabric as compared to more than 10,000 holes for the same yarn with a con ventional finish. (By adjusting the machine to normal, no holes would be formed with the yarn made according to this invention.)

Sweaters knit from this yarn are found to be free from pills after 100 hours of wear. This shows that the yarn is made of Weak fibers which ordinarily will not knit, but as a result of the finish the yarn knits satisfactorily. No static is developed during the processing of these fibers or the knitting of these yarns.

EXAMPLE II This example is to show that staple fiber finished in accordance with this invention can be carded, drafted, and spun satisfactorily.

A tow of 470,000 denier is prepared and finished as in Example I. It is next passed through a stuffer-box crimper to impart 10 to 15 crimps per inch (3.9 to 5.9 crimps per cm.). It is then cut into staple in lengths from 2.5 inches to 5.5 inches (6.3 to 14 cm.). This staple is carded on the Worsted system and spun into 30 Worsted count (266 denier) singles yarn with 11 Z turns per inch (4.3 per cm.) and two-piled with 6 S turns per inch (2.4 per cm.) in the ply.

No difiiculty is encountered in carding and a uniform Web is obtained free of neps. The sliver drafts readily with no breaks and gives a yarn with Lea Product of 1128 compared to 1051 for a conventional finish which gives a yarn which is not knittable. No static is observed in the carding and spinning of this fiber. The yarn made in accordance with this invention knits satisfactorily in the special knitting test described above.

EXAMPLE III Dispersions are made of the finish of Example I at solids concentrations of and The 25% dispersion has a viscosity of 209 centistokes and is capable of being applied to tow by conventional methods but the 30% dispersion is much too viscous for satisfactory application. Both of these dispersions are highly thixotrophic.

From the foregoing discussion, description and data, it is evident that the present discovery provides a significant advance in fiber preparation in that it provides finished fiber that can be knit without need to apply a special finish at the knitting machine. It Will be appreciated that the advanages of the inveniton can be realized in practices varying from the foregoing details. For example acrylic fibers other than the bicomponent exemplified can be similarly processed. The phosphate content of the composition may range from about 1.25 to 1.75 parts per part of parafiin wax. In addition additives in minor amounts may be included as long as they do not deleteriously alter the intended properties of the resulting finish. Other changes can be made without departing from the scope of this discovery.

What is claimed is:

1. Bicomponent textile fibers of synthetic acrylic polymer having on the surfaces thereof a finish composition consisting essentially, by weight, of 1.25 to 1.75 parts of a salt of a partial ester of phosphoric acid per part of a paraffin wax, said salt being an alkali metal salt of a monoor diester of phosphoric acid and at least one member of the group consisting of the condensation product of lauryl alcohol with 2 to 10 mols of alkylene oxide, the condensation product of decyl alcohol with 2 to 10 mols of alkylene oxide, the condensation product of tetradecyl alcohol with 4 to 16 mols of alkylene oxide, the condensation product of hexadecyl alcohol with 4 to 16 mols of alkylene oxide, the condensation product of hexadecenyl alcohol with 4 to 16 mols of alkylene oxide, the condensation product of nonyl phenol with 4 to 16 mols of alkylene oxide, the condensation product of decyl phenol with 4 to 16 mols of alkylene oxide and the condensation product of octyl phenol with 3 to 14 mols of alkylene oxide.

2. Textile fibers comprising bicomponent acrylic fibers in which the components are in side-by side relation along their length, one of the components being a polyacrylonitrile polymer and the other being a mixture of terpolyrner of acrylonitrile, methyl acrylate and sodium styrenesulfonate and copolymer of acrylonitrile and sodium styrenesulfonate, the fibers having on their surfaces about 0.1 to 0.8 percent, based on the fiber weight, of a finish composition consisting essentially of parts by weight of refined paraffin wax and parts by weight of the sodium salt of a mixture of monoand diesters of phosphoric acid and the condensate of lauryl alcohol with 4 mols of ethylene oxide.

References Cited UNITED STATES PATENTS 3,038,236 6/1962 Breen 2882 3,056,744 '10/1962 Copes et a1. 1l7l39.5 X 3,113,369 12/1963 Barrett et al. l17139.5 X

FOREIGN PATENTS 835,797 5/1969 Great Britain.

WILLIAM D. MARTIN, Primary Examiner.

J. E. MILLER, Assistant Examiner.

U.S. Cl. X.R. 

